2 * This file is part of UBIFS.
4 * Copyright (C) 2006-2008 Nokia Corporation.
6 * This program is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License version 2 as published by
8 * the Free Software Foundation.
10 * This program is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
15 * You should have received a copy of the GNU General Public License along with
16 * this program; if not, write to the Free Software Foundation, Inc., 51
17 * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
19 * Authors: Artem Bityutskiy (Битюцкий Артём)
24 * This file implements UBIFS extended attributes support.
26 * Extended attributes are implemented as regular inodes with attached data,
27 * which limits extended attribute size to UBIFS block size (4KiB). Names of
28 * extended attributes are described by extended attribute entries (xentries),
29 * which are almost identical to directory entries, but have different key type.
31 * In other words, the situation with extended attributes is very similar to
32 * directories. Indeed, any inode (but of course not xattr inodes) may have a
33 * number of associated xentries, just like directory inodes have associated
34 * directory entries. Extended attribute entries store the name of the extended
35 * attribute, the host inode number, and the extended attribute inode number.
36 * Similarly, direntries store the name, the parent and the target inode
37 * numbers. Thus, most of the common UBIFS mechanisms may be re-used for
38 * extended attributes.
40 * The number of extended attributes is not limited, but there is Linux
41 * limitation on the maximum possible size of the list of all extended
42 * attributes associated with an inode (%XATTR_LIST_MAX), so UBIFS makes sure
43 * the sum of all extended attribute names of the inode does not exceed that
46 * Extended attributes are synchronous, which means they are written to the
47 * flash media synchronously and there is no write-back for extended attribute
48 * inodes. The extended attribute values are not stored in compressed form on
51 * Since extended attributes are represented by regular inodes, they are cached
52 * in the VFS inode cache. The xentries are cached in the LNC cache (see
55 * ACL support is not implemented.
60 #include <linux/slab.h>
61 #include <linux/xattr.h>
64 * Limit the number of extended attributes per inode so that the total size
65 * (@xattr_size) is guaranteeded to fit in an 'unsigned int'.
67 #define MAX_XATTRS_PER_INODE 65535
70 * Extended attribute type constants.
72 * USER_XATTR: user extended attribute ("user.*")
73 * TRUSTED_XATTR: trusted extended attribute ("trusted.*)
74 * SECURITY_XATTR: security extended attribute ("security.*")
82 static const struct inode_operations empty_iops;
83 static const struct file_operations empty_fops;
86 * create_xattr - create an extended attribute.
87 * @c: UBIFS file-system description object
89 * @nm: extended attribute name
90 * @value: extended attribute value
91 * @size: size of extended attribute value
93 * This is a helper function which creates an extended attribute of name @nm
94 * and value @value for inode @host. The host inode is also updated on flash
95 * because the ctime and extended attribute accounting data changes. This
96 * function returns zero in case of success and a negative error code in case
99 static int create_xattr(struct ubifs_info *c, struct inode *host,
100 const struct fscrypt_name *nm, const void *value, int size)
104 struct ubifs_inode *ui, *host_ui = ubifs_inode(host);
105 struct ubifs_budget_req req = { .new_ino = 1, .new_dent = 1,
106 .new_ino_d = ALIGN(size, 8), .dirtied_ino = 1,
107 .dirtied_ino_d = ALIGN(host_ui->data_len, 8) };
109 if (host_ui->xattr_cnt >= MAX_XATTRS_PER_INODE) {
110 ubifs_err(c, "inode %lu already has too many xattrs (%d), cannot create more",
111 host->i_ino, host_ui->xattr_cnt);
115 * Linux limits the maximum size of the extended attribute names list
116 * to %XATTR_LIST_MAX. This means we should not allow creating more
117 * extended attributes if the name list becomes larger. This limitation
118 * is artificial for UBIFS, though.
120 names_len = host_ui->xattr_names + host_ui->xattr_cnt + fname_len(nm) + 1;
121 if (names_len > XATTR_LIST_MAX) {
122 ubifs_err(c, "cannot add one more xattr name to inode %lu, total names length would become %d, max. is %d",
123 host->i_ino, names_len, XATTR_LIST_MAX);
127 err = ubifs_budget_space(c, &req);
131 inode = ubifs_new_inode(c, host, S_IFREG | S_IRWXUGO);
133 err = PTR_ERR(inode);
137 /* Re-define all operations to be "nothing" */
138 inode->i_mapping->a_ops = &empty_aops;
139 inode->i_op = &empty_iops;
140 inode->i_fop = &empty_fops;
142 inode->i_flags |= S_SYNC | S_NOATIME | S_NOCMTIME | S_NOQUOTA;
143 ui = ubifs_inode(inode);
145 ui->flags |= UBIFS_XATTR_FL;
146 ui->data = kmemdup(value, size, GFP_NOFS);
151 inode->i_size = ui->ui_size = size;
154 mutex_lock(&host_ui->ui_mutex);
155 host->i_ctime = ubifs_current_time(host);
156 host_ui->xattr_cnt += 1;
157 host_ui->xattr_size += CALC_DENT_SIZE(fname_len(nm));
158 host_ui->xattr_size += CALC_XATTR_BYTES(size);
159 host_ui->xattr_names += fname_len(nm);
162 * We handle UBIFS_XATTR_NAME_ENCRYPTION_CONTEXT here because we
163 * have to set the UBIFS_CRYPT_FL flag on the host inode.
164 * To avoid multiple updates of the same inode in the same operation,
167 if (strcmp(fname_name(nm), UBIFS_XATTR_NAME_ENCRYPTION_CONTEXT) == 0)
168 host_ui->flags |= UBIFS_CRYPT_FL;
170 err = ubifs_jnl_update(c, host, nm, inode, 0, 1);
173 mutex_unlock(&host_ui->ui_mutex);
175 ubifs_release_budget(c, &req);
176 insert_inode_hash(inode);
181 host_ui->xattr_cnt -= 1;
182 host_ui->xattr_size -= CALC_DENT_SIZE(fname_len(nm));
183 host_ui->xattr_size -= CALC_XATTR_BYTES(size);
184 host_ui->xattr_names -= fname_len(nm);
185 host_ui->flags &= ~UBIFS_CRYPT_FL;
186 mutex_unlock(&host_ui->ui_mutex);
188 make_bad_inode(inode);
191 ubifs_release_budget(c, &req);
196 * change_xattr - change an extended attribute.
197 * @c: UBIFS file-system description object
199 * @inode: extended attribute inode
200 * @value: extended attribute value
201 * @size: size of extended attribute value
203 * This helper function changes the value of extended attribute @inode with new
204 * data from @value. Returns zero in case of success and a negative error code
205 * in case of failure.
207 static int change_xattr(struct ubifs_info *c, struct inode *host,
208 struct inode *inode, const void *value, int size)
211 struct ubifs_inode *host_ui = ubifs_inode(host);
212 struct ubifs_inode *ui = ubifs_inode(inode);
215 struct ubifs_budget_req req = { .dirtied_ino = 2,
216 .dirtied_ino_d = ALIGN(size, 8) + ALIGN(host_ui->data_len, 8) };
218 ubifs_assert(ui->data_len == inode->i_size);
219 err = ubifs_budget_space(c, &req);
223 buf = kmemdup(value, size, GFP_NOFS);
228 mutex_lock(&ui->ui_mutex);
231 inode->i_size = ui->ui_size = size;
232 old_size = ui->data_len;
234 mutex_unlock(&ui->ui_mutex);
236 mutex_lock(&host_ui->ui_mutex);
237 host->i_ctime = ubifs_current_time(host);
238 host_ui->xattr_size -= CALC_XATTR_BYTES(old_size);
239 host_ui->xattr_size += CALC_XATTR_BYTES(size);
242 * It is important to write the host inode after the xattr inode
243 * because if the host inode gets synchronized (via 'fsync()'), then
244 * the extended attribute inode gets synchronized, because it goes
245 * before the host inode in the write-buffer.
247 err = ubifs_jnl_change_xattr(c, inode, host);
250 mutex_unlock(&host_ui->ui_mutex);
252 ubifs_release_budget(c, &req);
256 host_ui->xattr_size -= CALC_XATTR_BYTES(size);
257 host_ui->xattr_size += CALC_XATTR_BYTES(old_size);
258 mutex_unlock(&host_ui->ui_mutex);
259 make_bad_inode(inode);
261 ubifs_release_budget(c, &req);
265 static struct inode *iget_xattr(struct ubifs_info *c, ino_t inum)
269 inode = ubifs_iget(c->vfs_sb, inum);
271 ubifs_err(c, "dead extended attribute entry, error %d",
272 (int)PTR_ERR(inode));
275 if (ubifs_inode(inode)->xattr)
277 ubifs_err(c, "corrupt extended attribute entry");
279 return ERR_PTR(-EINVAL);
282 int ubifs_xattr_set(struct inode *host, const char *name, const void *value,
283 size_t size, int flags)
286 struct ubifs_info *c = host->i_sb->s_fs_info;
287 struct fscrypt_name nm = { .disk_name = FSTR_INIT((char *)name, strlen(name))};
288 struct ubifs_dent_node *xent;
293 * Creating an encryption context is done unlocked since we
294 * operate on a new inode which is not visible to other users
297 if (strcmp(name, UBIFS_XATTR_NAME_ENCRYPTION_CONTEXT) != 0)
298 ubifs_assert(inode_is_locked(host));
300 if (size > UBIFS_MAX_INO_DATA)
303 if (fname_len(&nm) > UBIFS_MAX_NLEN)
304 return -ENAMETOOLONG;
306 xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
311 * The extended attribute entries are stored in LNC, so multiple
312 * look-ups do not involve reading the flash.
314 xent_key_init(c, &key, host->i_ino, &nm);
315 err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
320 if (flags & XATTR_REPLACE)
321 /* We are asked not to create the xattr */
324 err = create_xattr(c, host, &nm, value, size);
328 if (flags & XATTR_CREATE) {
329 /* We are asked not to replace the xattr */
334 inode = iget_xattr(c, le64_to_cpu(xent->inum));
336 err = PTR_ERR(inode);
340 err = change_xattr(c, host, inode, value, size);
348 ssize_t ubifs_xattr_get(struct inode *host, const char *name, void *buf,
352 struct ubifs_info *c = host->i_sb->s_fs_info;
353 struct fscrypt_name nm = { .disk_name = FSTR_INIT((char *)name, strlen(name))};
354 struct ubifs_inode *ui;
355 struct ubifs_dent_node *xent;
359 if (fname_len(&nm) > UBIFS_MAX_NLEN)
360 return -ENAMETOOLONG;
362 xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
366 xent_key_init(c, &key, host->i_ino, &nm);
367 err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
374 inode = iget_xattr(c, le64_to_cpu(xent->inum));
376 err = PTR_ERR(inode);
380 ui = ubifs_inode(inode);
381 ubifs_assert(inode->i_size == ui->data_len);
382 ubifs_assert(ubifs_inode(host)->xattr_size > ui->data_len);
384 mutex_lock(&ui->ui_mutex);
386 /* If @buf is %NULL we are supposed to return the length */
387 if (ui->data_len > size) {
388 ubifs_err(c, "buffer size %zd, xattr len %d",
394 memcpy(buf, ui->data, ui->data_len);
399 mutex_unlock(&ui->ui_mutex);
406 static bool xattr_visible(const char *name)
408 /* File encryption related xattrs are for internal use only */
409 if (strcmp(name, UBIFS_XATTR_NAME_ENCRYPTION_CONTEXT) == 0)
412 /* Show trusted namespace only for "power" users */
413 if (strncmp(name, XATTR_TRUSTED_PREFIX,
414 XATTR_TRUSTED_PREFIX_LEN) == 0 && !capable(CAP_SYS_ADMIN))
420 ssize_t ubifs_listxattr(struct dentry *dentry, char *buffer, size_t size)
423 struct inode *host = d_inode(dentry);
424 struct ubifs_info *c = host->i_sb->s_fs_info;
425 struct ubifs_inode *host_ui = ubifs_inode(host);
426 struct ubifs_dent_node *xent, *pxent = NULL;
427 int err, len, written = 0;
428 struct fscrypt_name nm = {0};
430 dbg_gen("ino %lu ('%pd'), buffer size %zd", host->i_ino,
433 len = host_ui->xattr_names + host_ui->xattr_cnt;
436 * We should return the minimum buffer size which will fit a
437 * null-terminated list of all the extended attribute names.
444 lowest_xent_key(c, &key, host->i_ino);
446 xent = ubifs_tnc_next_ent(c, &key, &nm);
452 fname_name(&nm) = xent->name;
453 fname_len(&nm) = le16_to_cpu(xent->nlen);
455 if (xattr_visible(xent->name)) {
456 memcpy(buffer + written, fname_name(&nm), fname_len(&nm) + 1);
457 written += fname_len(&nm) + 1;
462 key_read(c, &xent->key, &key);
466 if (err != -ENOENT) {
467 ubifs_err(c, "cannot find next direntry, error %d", err);
471 ubifs_assert(written <= size);
475 static int remove_xattr(struct ubifs_info *c, struct inode *host,
476 struct inode *inode, const struct fscrypt_name *nm)
479 struct ubifs_inode *host_ui = ubifs_inode(host);
480 struct ubifs_inode *ui = ubifs_inode(inode);
481 struct ubifs_budget_req req = { .dirtied_ino = 2, .mod_dent = 1,
482 .dirtied_ino_d = ALIGN(host_ui->data_len, 8) };
484 ubifs_assert(ui->data_len == inode->i_size);
486 err = ubifs_budget_space(c, &req);
490 mutex_lock(&host_ui->ui_mutex);
491 host->i_ctime = ubifs_current_time(host);
492 host_ui->xattr_cnt -= 1;
493 host_ui->xattr_size -= CALC_DENT_SIZE(fname_len(nm));
494 host_ui->xattr_size -= CALC_XATTR_BYTES(ui->data_len);
495 host_ui->xattr_names -= fname_len(nm);
497 err = ubifs_jnl_delete_xattr(c, host, inode, nm);
500 mutex_unlock(&host_ui->ui_mutex);
502 ubifs_release_budget(c, &req);
506 host_ui->xattr_cnt += 1;
507 host_ui->xattr_size += CALC_DENT_SIZE(fname_len(nm));
508 host_ui->xattr_size += CALC_XATTR_BYTES(ui->data_len);
509 host_ui->xattr_names += fname_len(nm);
510 mutex_unlock(&host_ui->ui_mutex);
511 ubifs_release_budget(c, &req);
512 make_bad_inode(inode);
516 static int ubifs_xattr_remove(struct inode *host, const char *name)
519 struct ubifs_info *c = host->i_sb->s_fs_info;
520 struct fscrypt_name nm = { .disk_name = FSTR_INIT((char *)name, strlen(name))};
521 struct ubifs_dent_node *xent;
525 ubifs_assert(inode_is_locked(host));
527 if (fname_len(&nm) > UBIFS_MAX_NLEN)
528 return -ENAMETOOLONG;
530 xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
534 xent_key_init(c, &key, host->i_ino, &nm);
535 err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
542 inode = iget_xattr(c, le64_to_cpu(xent->inum));
544 err = PTR_ERR(inode);
548 ubifs_assert(inode->i_nlink == 1);
550 err = remove_xattr(c, host, inode, &nm);
554 /* If @i_nlink is 0, 'iput()' will delete the inode */
562 static int init_xattrs(struct inode *inode, const struct xattr *xattr_array,
565 const struct xattr *xattr;
569 for (xattr = xattr_array; xattr->name != NULL; xattr++) {
570 name = kmalloc(XATTR_SECURITY_PREFIX_LEN +
571 strlen(xattr->name) + 1, GFP_NOFS);
576 strcpy(name, XATTR_SECURITY_PREFIX);
577 strcpy(name + XATTR_SECURITY_PREFIX_LEN, xattr->name);
578 err = ubifs_xattr_set(inode, name, xattr->value,
579 xattr->value_len, 0);
588 int ubifs_init_security(struct inode *dentry, struct inode *inode,
589 const struct qstr *qstr)
593 err = security_inode_init_security(inode, dentry, qstr,
596 struct ubifs_info *c = dentry->i_sb->s_fs_info;
597 ubifs_err(c, "cannot initialize security for inode %lu, error %d",
603 static int xattr_get(const struct xattr_handler *handler,
604 struct dentry *dentry, struct inode *inode,
605 const char *name, void *buffer, size_t size)
607 dbg_gen("xattr '%s', ino %lu ('%pd'), buf size %zd", name,
608 inode->i_ino, dentry, size);
610 name = xattr_full_name(handler, name);
611 return ubifs_xattr_get(inode, name, buffer, size);
614 static int xattr_set(const struct xattr_handler *handler,
615 struct dentry *dentry, struct inode *inode,
616 const char *name, const void *value,
617 size_t size, int flags)
619 dbg_gen("xattr '%s', host ino %lu ('%pd'), size %zd",
620 name, inode->i_ino, dentry, size);
622 name = xattr_full_name(handler, name);
625 return ubifs_xattr_set(inode, name, value, size, flags);
627 return ubifs_xattr_remove(inode, name);
630 static const struct xattr_handler ubifs_user_xattr_handler = {
631 .prefix = XATTR_USER_PREFIX,
636 static const struct xattr_handler ubifs_trusted_xattr_handler = {
637 .prefix = XATTR_TRUSTED_PREFIX,
642 static const struct xattr_handler ubifs_security_xattr_handler = {
643 .prefix = XATTR_SECURITY_PREFIX,
648 const struct xattr_handler *ubifs_xattr_handlers[] = {
649 &ubifs_user_xattr_handler,
650 &ubifs_trusted_xattr_handler,
651 &ubifs_security_xattr_handler,